S4 methods metaprogramming in R

Question

Here is an example:

setGeneric("loadBim",
        function(pl_info, ...) {
            standardGeneric("loadBim")
        })

setMethod("loadBim",
        signature(pl_info = "PlInfo"),
        function(pl_info) {
            loadFFDF(pl_info@ff_dir_trio["bim"])
        })
setGeneric("loadFam",
        function(pl_info, ...) {
            standardGeneric("loadFam")
        })

setMethod("loadFam",
        signature(pl_info = "PlInfo"),
        function(pl_info) {
            loadFFDF(pl_info@ff_dir_trio["fam"])
        })

setGeneric("loadFrq",
        function(pl_info, ...) {
            standardGeneric("loadFrq")
        })

setMethod("loadFrq",
        signature(pl_info = "PlInfo"),
        function(pl_info) {
            loadFFDF(pl_info@ff_dir_trio["frq"])
        })

All these S4 methods are similar, they differ only for some file extension names: bim, fam, and frq. I am wondering is there some metaproramming technique available for simplifying them (generating them programmatically)?

Answer 1

I found out one solution:

loadPlinkMeta = gtools::defmacro(ext, method_name, expr = {
    setGeneric(method_name, 
            function(pl_info, ...) {
                standardGeneric(method_name)
            })
    setMethod(method_name, 
            signature(pl_info = "PlInfo"), 
            function(pl_info) {
                loadFFDF(pl_info@ff_dir_trio[ext])
            })
})

loadPlinkMeta("bim", "loadBim")
loadPlinkMeta("fam", "loadFam")
loadPlinkMeta("frq", "loadFrq")